JP2018144284A - Screen mask and method for producing screen mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screen mask, a screen printer, and a method for producing printed matter that can secure the discharge amount with high accuracy.SOLUTION: A screen mask according to one embodiment has a support material having a hole that allows the passage of an application material, and a mask film that is provided in the support material, and has a pattern opening having a step or an inflection part in the middle of the film in the thickness direction, with an opening width on the print surface side being narrower than that of the opposite side.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a screen mask and a method for manufacturing the screen mask.

  Screen printing, which is one of the printing methods, is a method of forming an arbitrary printed body on a printing material using a screen mask in which a predetermined pattern opening formed of a resin composition is formed on a mesh as a support material. . This screen printing method is used for various printing such as wiring, electrodes, and fluorescent material printing, and is used in various fields including electronic components.

  In recent years, high precision of screen masks has been demanded due to miniaturization and high quality of electronic components.

  For example, the screen mask includes a mesh having holes that can pass through the coating material, and a mask film that is provided in the mesh and has a pattern opening. The pattern opening formed in the mask film has a shape corresponding to, for example, a printing pattern, and generally has a constant width in the entire length in the thickness direction. For example, after an emulsion for forming a mask film is applied to a mesh, a pattern opening is formed by an exposure process in which a photomask is overlaid.

JP 2013-169783 A

  In such a screen mask, there is a demand for a screen mask and a method for manufacturing the screen mask that can secure a discharge amount with high accuracy.

  A screen mask according to an aspect of the present invention includes a support material having a hole through which a coating material can permeate, and a support surface provided on the support material and having a step or an inflection part in the middle of the film thickness direction. And a mask film having a pattern opening whose opening width on the side is narrower than the opening width on the opposite side.

  According to the embodiments of the present invention, it is possible to provide a screen mask capable of high-precision printing and a method for manufacturing the screen mask.

Explanatory drawing of the screen printing apparatus concerning 1st Embodiment. The perspective view of the screen mask concerning the embodiment. Sectional drawing of the screen mask. Explanatory drawing which shows the structure of the pattern opening of the screen mask. Explanatory drawing which shows the manufacturing method of the screen mask. Explanatory drawing which shows the relationship between the shape of the pattern opening of the same screen mask and a comparative example, the resolution, and the discharge amount. Explanatory drawing which shows the relationship between the shape of the same screen mask, resolution, and smoothness. Explanatory drawing which shows the structure of the modification of the screen mask. Explanatory drawing which shows the structure of the modification of the screen mask. Explanatory drawing which shows the structure of the screen mask concerning other embodiment.

[First Embodiment]
Hereinafter, a screen printing apparatus 10 and a screen mask 20 according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is an explanatory diagram showing a screen printing apparatus 10 according to the present embodiment. 2 is a perspective view of the screen mask 20, and FIG. 3 is a cross-sectional view thereof. In each figure, for the sake of explanation, the configuration is appropriately enlarged, reduced, and omitted. In the figure, arrows X, Y, and Z indicate three directions orthogonal to each other.

  As shown in FIG. 1, the screen printing apparatus 10 includes a screen mask 20, a holding member 12 that holds a printing medium Ba facing a surface (one surface) 20 a that is a printing surface side of the screen mask 20, a screen The squeegee 13 is configured to be movable in contact with the back surface (the other surface) 20b opposite to the printing surface side of the mask 20, the moving unit for moving the squeegee 13, and the screen mask 20 to the printing medium Ba. And a support part that supports the opposite.

  The screen printing apparatus 10 forms various printing materials in a predetermined pattern on the surface of the printing medium Ba. For example, chip components (capacitors, chip resistors, inductors, thermistors, etc.), touch panels, liquid crystal substrates (LCD) seals, LTCC (Low Temperature Co-fired ceramics) substrates, solar cell electrodes, other electronic components Used in the manufacture of

  As shown in FIGS. 1 and 2, the screen mask 20 includes a frame 21, a mesh 22 that is a support material stretched on the frame 21, and a mask film 23 formed on the mesh 22. In the screen mask 20, the side facing the surface of the print medium Ba when performing printing is the front surface 20 a, and the opposite side to which the coating material Pe is supplied is the back surface 20 b.

  The frame 21 has two pairs of sides parallel to each other, and is configured in a frame shape having a square opening of a desired size, for example. The frame 21 supports the outer peripheral edge of the mesh 22 and stretches the mesh 22 in the opening. In this embodiment, as an example, the Y-direction dimension Fy of the opening of the frame 21 is 275 mm, and the X-direction dimension Fx is 275 mm.

  The frame 21 also functions as a frame that holds a predetermined amount of the coating material Pe on the back side of the mask film 23. The frame 21 and the mesh 22 are joined at a joint portion by, for example, a synthetic rubber or cyanoacrylate adhesive.

  The mesh 22 is a woven fabric formed by knitting warps 22a and wefts 22b, and has a large number of holes 22c that are open to allow the coating material Pe to pass therethrough. The warp yarn 22a and the weft yarn 22b are, for example, fibers made of a metal wire such as stainless steel or a resin such as polyester. The warp yarn 22a and the weft yarn 22b extend obliquely with respect to the moving direction of the squeegee 13, for example.

  A mask film 23 having a predetermined pattern opening 23 a is formed on the mesh 22. That is, the mask film 23 is held in the opening portion of the frame 21 by the mesh 22.

  The mask film 23 is a layer made of a photocurable resin composition such as PVA, PVAc, silicon resin, acrylic resin, epoxy resin, or the like.

  The thickness t0 of the mask film 23 is, for example, 10 μm to 100 μm. A thickness tm of a portion of the mask film 23 on the printing surface side (for example, the upper side in FIG. 3) of the mesh 22, that is, a portion protruding to the front side of the mesh 22 is referred to as milk thickness. The milk thickness tm is preferably set to 0 μm to 50 μm.

  The mask film 23 is formed on the mesh 22 and is disposed in the opening portion of the frame 21. A predetermined pattern opening 23a for printing is formed in the mask film 23 by exposure.

  The minimum opening width of the pattern opening 23a, that is, the width dimension of the opening in the narrowest part of the pattern opening 23a is 30 μm or less. Here, as an example, the dimension on the surface of the mask film 23, that is, the surface 20a facing the print medium Ba is used as a reference.

  The pattern opening 23a is a line-shaped pattern hole. The pattern opening 23a has a step 23c in the middle in the depth direction, and two inflection portions are formed on the side wall of the pattern opening 23a by the step 23c. In other words, the pattern opening 23a has a large portion R1 on the squeegee side and a small width portion R2 on the printing surface side through the inflection portion due to the step 23c. The large portion R1 and the narrow portion R2 are continuous and form a slit corresponding to the print pattern and penetrating the mask film 23 in the depth direction. Here, the depth dimension d1 of the large portion R1 is larger than the depth dimension d2 of the small width portion R2, and the step 23c is disposed closer to the printing surface than the intermediate position in the depth direction. The pattern opening 23a is configured such that the width dimension Wb of the small width portion R2 on the printing surface side, that is, the surface 20a is narrowed. The opening width Wa on the surface 20a that is the end of the small width portion R2 is configured to be smaller than the width Wb of the large portion R1 in the vicinity of the step 23c. The width of the step 23c, that is, the aperture width ΔW on one side surface is 20 μm or less, and satisfies (Wb−Wa) / 2 ≦ 20 μm. Further, the large portion R1 and the small width portion R2 of the pattern opening 23a have a cylindrical shape with a substantially constant diameter, and the inner peripheral surfaces of the large portion R1 and the small width portion R2 are configured to be substantially parallel. Specifically, the inner peripheral surfaces of the large portion R1 and the small width portion R2 are both set to have an inclination angle within 20 degrees with respect to the axial direction of the pattern opening 23a, and are preferably parallel. That is, each of the large portion R1 and the small width portion R2 has a constant cross-sectional shape and an opening width.

The pattern opening 23a satisfies the relational expression ΔW ≦ ΔT ≦ 2 / 3T.
Here, ΔW = (Wb−Wa) / 2 ≦ 20 μm, T: Total thickness (thickness including mesh and emulsion thickness), ΔT: Step thickness from P plane, ΔW: Step width on one side from line width is there.

  The mask film 23 forms a printing part in which the photosensitive resin does not exist in the pattern opening 23 a and passes through the holes of the mesh 22 so that the coating material Pe can be transmitted from the back surface to the front surface. A portion other than the pattern opening 23a of the mask film 23 and where the hole portion of the mesh 22 is blocked with a photosensitive resin constitutes a non-printing portion that does not transmit ink as the coating material Pe.

  The mesh 22 on which the mask film 23 is formed is configured to be elastically deformable so as to be bent and deformed by a pressing force by the squeegee 13, for example, and restored when the pressing force is released. In a state where the coating material Pe is held in the pattern opening 23a of the mask film 23, the coating film Pe is brought into contact with and separated from the printing medium Ba by elastic deformation of the mesh 22, so that the coating material Pe is transferred from the pattern opening 23a to the printing medium Ba. Transcribed.

  The squeegee 13 is made of a material such as urethane rubber, silicon rubber, synthetic rubber, metal or plastic, for example, in a thin plate shape. For example, the squeegee 13 is chamfered so that the thickness of the tip is reduced. The squeegee 13 is configured to be able to reciprocate with respect to the frame 21. For example, the squeegee 13 has a length extending over the entire length of the mask film 23 in a direction orthogonal to the moving direction. In the state where the tip portion 13a of the squeegee 13 is in contact with the back surface 20b of the screen mask 20 and pressed to the front side, the entire surface of the mask film 23 is pressed and moved by moving in the moving direction along the arrow A in FIG. The coating material Pe is extruded to the front side from the pattern opening 23a pre-filled with the material Pe.

  The support unit supports the frame 21 in parallel with the print medium Ba at a predetermined interval C1. The moving unit moves the squeegee 13 along a predetermined direction at a predetermined speed.

  Next, a method for manufacturing the screen mask 20 according to the present embodiment will be described with reference to FIG. FIG. 5 is an explanatory diagram showing a method for manufacturing the screen mask 20. The method for manufacturing the screen mask 20 includes an emulsion Pm coating process and an exposure process.

  The emulsion Pm is a photocurable resin, and is a liquid including, for example, polyvinyl alcohol (PVA), polyvinyl acetate (PVAc), silicon resin, acrylic resin, epoxy resin, and the like.

  First, the mesh 22 is attached to the frame 21 so as to be substantially flat. In this state, a coating process for coating the emulsion Pm on the mesh 22 is performed. In the application process, the mesh 22 is applied to the surface of the mesh 22 using a supply bucket containing the emulsion Pm in a state where the mesh 22 is installed in a substantially vertical direction (ST1).

  At this time, the emulsion Pm is formed in a flat plate shape on the mesh 22 by moving the bucket arranged at a predetermined position from below to above and applying the emulsion Pm while flattening it at the edge of the bucket. The At this time, since the thickness changes according to the number of times of application, the application is repeated a plurality of times as necessary. Further, the film thickness is measured after drying, and in some cases, it may be additionally applied. In the present embodiment, the thickness of the emulsion Pm is set so that the milk thickness tm is about 10 μm after drying.

  Next, as shown in ST2, a maskless exposure process is performed by a maskless exposure machine that does not use a photomask. Specifically, the surface side of the emulsion Pm is arranged in a predetermined exposure pattern area so as to face the illumination 28 such as an ultraviolet lamp or an ultraviolet LED, and light is irradiated by the illumination 28 to illuminate the surface of the emulsion Pm. Perform twice under different conditions. By the exposure process, the portion of the emulsion Pm irradiated with the ultraviolet rays corresponding to the exposed pattern region is cured by the ultraviolet rays.

In the exposure process, a first exposure process (ST2) for forming the narrow portion R2 and a second exposure process (ST3) for forming the large portion R1 are performed. Both the first exposure process and the second exposure process are exposure processes in which light is irradiated from the printing surface side. In the first exposure process, a shallow predetermined range H2 is hardened by performing exposure under the condition of an exposure amount of 250 mJ / cm ² with a pattern for a wide region.

The second exposure process is a pattern that targets a narrower area than the first exposure process in the same direction as the first exposure process, and is exposed under the condition of an exposure amount of 750 mJ / cm ² . The predetermined range H1 deeper than the first exposure process is cured.

  Thereafter, as the etching process, the surface side of the emulsion Pm is washed away with water or a solvent. By this treatment, as shown in ST4, the uncured portion of the emulsion Pm is washed away. That is, in the layer of the emulsion Pm, all uncured regions are washed away, and a pattern opening 23a having a step 23c that penetrates from the front surface side to the back surface side in the thickness direction and forms an inflection portion is formed. Thus, a mask film 23 having a pattern opening 23a having a predetermined shape is formed from the emulsion Pm.

  Next, a method for producing a printed matter by a screen printing method using the screen printing apparatus 10 according to the present embodiment will be described with reference to FIG. First, the screen mask 20 is disposed so that the surface side of the screen mask 20 faces the surface of the print medium Ba held by the holding member 12.

  Then, as shown by a two-dot chain line in FIG. 1, a high-viscosity paste-like coating material Pe is supplied from the back side of the screen mask 20, that is, the surface opposite to the printing medium Ba, and the coating material Pe is patterned. The opening 23a is filled.

  Next, the squeegee 13 is arranged on the back surface 20b of the screen mask 20, that is, the surface opposite to the printing surface side. At this time, for example, the squeegee 13 is arranged at a predetermined angle with respect to the front side surface of the print medium Ba. Then, the squeegee 13 is moved at a predetermined speed while pressing the squeegee 13 on the back surface of the mesh 22 and the mask film 23 toward the printing medium Ba with a predetermined printing pressure. The squeegee 13 presses the mask film 23 in a region covering the entire back surface of the mask film 23. By the pressing of the squeegee 13, the mask film 23 is deformed so that the pressed portion is displaced to the front side, and comes into contact with the printing medium Ba. The coating material Pe that has passed through the squeegee 13 is pushed out from the pattern opening 23a toward the print medium Ba.

  After the squeegee 13 passes, the mask film 23 and the mesh 22 are deformed so as to be restored and separated from the print medium Ba, and a part of the coating material Pe is transferred and left on the print medium Ba, thereby leaving the print medium Ba. Pattern printing is performed on the top to complete the printed matter. At this time, a part of the back side of the coating material Pe remains on the mask film 23 side. The coating material Pe is a variety of materials including, for example, a metal material and a resin material, and various materials are used depending on the type of print target, for example, an electronic component, a display, and the like.

  According to the screen mask 20, the screen printing apparatus 10, and the screen printing method configured as described above, printing with a high discharge amount and high accuracy is possible. That is, since the pattern opening 23a has a step 23c and a stepped shape in which the opening on the printing surface side becomes narrow, a high discharge amount and high resolution can be realized.

  FIG. 6 shows the shapes of various pattern openings, the printing resolution, the discharge amount, and the exposure method. An opening 23a having a step where the opening width on the printing surface side according to the present embodiment is narrowed, and an opening 123a having an inflection portion where the opening width on the printing surface side is a first modification of the present embodiment, The opening 223a which has two steps of the inflection part which becomes narrow the opening width by the side of the printing surface which is the 2nd modification of this embodiment is shown. Further, as comparative objects, a comparative example 1 of a so-called straight type in which the opening width is constant, a comparative example 2 in which the opening width changes in a tapered shape so that the printing surface side becomes wider, and an opening width at the center in the depth direction. A comparative example 3 having a tapered shape on both sides and a comparative example 4 in which the opening width changes in a tapered shape so that the printing surface side becomes narrow are shown.

  As shown in FIG. 6, the openings 23 a, 123 a, and 223 a having a stepped shape in which the opening on the printing surface side becomes narrower have the opening shapes of Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4. In comparison, a high discharge amount and high resolution can be realized.

  Moreover, according to the said embodiment, since the large part R1 and the small width part R2 are cylindrical shape with a substantially constant diameter, and the internal peripheral surface of the large part R1 and the small width part R2 is comprised substantially parallel, more Even when a high-definition pattern is formed, the effect of maintaining the emulsion strength can be obtained. In other words, by adopting a configuration in which the inner peripheral wall surface is arranged along the axial direction, for example, a higher resolution and a higher discharge amount are realized as compared with the case where the large portion R1 and the small width portion R2 have a tapered shape whose diameter changes. The effect that it can be obtained.

  In addition, the pattern opening 23a is configured to satisfy the relational expression of ΔW ≦ ΔT ≦ 2 / 3T, so that the filling amount and smoothness can be maintained. That is, as shown in FIG. 7, when ΔW> ΔT, the thickness of the emulsion on the printing surface side is too thin and easily deforms, whereas when ΔT> 2 / 3T, the discharge amount decreases. On the other hand, by adopting a configuration satisfying ΔW ≦ ΔT ≦ 2 / 3T, the shape of the mask film on the printing surface can be maintained, and the discharge amount can be secured.

  Further, according to the present embodiment, both the first exposure process and the second exposure process are exposure processes in which light is irradiated from the printing surface side, and the conditions such as the exposure amount and the exposure time are made different. It is possible to easily form a stepped pattern opening.

  Note that the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage.

FIG. 8 is an explanatory view showing the pattern openings 23a having different sizes in comparison. Here, an example in which the width of the step 23c is 3 μm, 5 μm, and 7 μm is shown. Even in these cases,
For example, in the above embodiment, the pattern opening 23a is an example in which the diameters of the large portion R1 and the small width portion R2 are constant, but the present invention is not limited thereto. For example, the pattern opening 123a shown as a first modification in FIG. 6 is configured in a shape in which the step 123c and the edge of the surface draw a gentle curve. Even with this structure, the configuration having the inflection portion so that the printing surface side is narrowed can provide the same effect as the stepped pattern opening 23a, and high resolution and high discharge amount can be realized.

  Further, the number of stages is not limited to one. For example, a pattern opening 223a shown as a second modification in FIG. 9 has two steps 223c. The pattern opening 223a has a middle width portion R3 (medium diameter portion) between a small width portion R1 (small diameter portion) on the printing surface side and a large portion R2 (large diameter portion) on the opposite side. The diameter portion R3 and the large portion R2 are continuous in the axial direction. The opening widths (opening diameters) of the small width portion R1, the middle width portion R3, and the large width portion R2 satisfy R1 <R2 <R3.

The pattern opening 223a satisfies the following conditions: ΔW ≦ ΔT ≦ 2 / 3T, ΔW = (Wb−Wa) / 2 ≦ 20 μm, ΔW _n <ΔW, ΔW _n ≦ ΔT _n ≦ 2 / 3T, ΔW _n <ΔW. It was. Here, T is the total thickness (thickness including the thickness of the mesh and emulsion), ΔT is the step thickness from the P plane, and ΔW is the step width on one side from the line width.

  Even in the structure of the pattern opening 223a, the stepped structure having the inflection portion so that the printing surface side is narrowed can provide the same effect as the pattern opening 23a, and can have a high resolution and a high discharge amount. Can be realized. Similarly, even if there are three or more steps, the same effect as the pattern opening 23a can be obtained.

  In the above embodiment, an example in which the mesh 22 is attached to the frame 21 with the adhesive 24 and the mask film 23 is formed over the entire opening of the frame 21 has been described, but the present invention is not limited to this. For example, a so-called combination type may be used for the mesh, and the mask film 23 may be formed only on a part of the central portion of the mesh 22.

  In another embodiment, the screen mask 20A shown in FIG. 10 is a so-called combination in which a mesh 22 is connected to an inner main mesh 26 and an outer support mesh 27 having different elongation rates by being fixed with a UV curable adhesive. It consists of a mold. The mesh 22 according to the present embodiment holds the mask film 23 in the opening portion of the frame 21.

  The main mesh 26 is a woven fabric formed by knitting warps 26a and wefts 26b, and has a large number of holes 26c that are open to allow the coating material Pe to pass therethrough. The warps 26a and the wefts 26b are fibers made of a metal wire such as stainless steel or a resin such as polyester. The warps 26a and the wefts 26b extend obliquely with respect to the moving direction of the squeegee 13 along the arrow A, for example.

  The main mesh 26 is configured in a rectangular shape whose dimension in the Y direction is larger than that in the X direction. In the present embodiment, as an example, the dimension My in the Y direction is 230 mm, and the dimension Mx in the X direction is 200 mm.

  The support mesh 27 is joined to the outer periphery of the main mesh 26 with an adhesive 24. The support mesh 27 is a woven fabric formed by knitting warps 26a and wefts 27b. The support mesh 27 is configured to have a higher elongation rate than the main mesh 26.

  In the screen mask 20A according to the present embodiment, in the first direction, which is the moving direction of the squeegee, the size ratio of the main mesh to the size of the mesh portion is larger than the size ratio in the second direction orthogonal to the one direction. The elastic strength ratio, which is the ratio between the tensile elastic modulus of the support mesh and the tensile elastic modulus of the main mesh, is 10% or more and 25% or less, and the amount of elongation in the second direction at the time of printing the main mesh is It is set within the range of change in elongation.

  For example, the size ratio of the main mesh in the second direction is 40% or more and 90% or less of the size ratio in the first direction. Further, the tensile elastic modulus (Young's modulus) of the support mesh 27 was set to be within a range of 10% to 25% of the tensile elastic modulus of the main mesh 26, and was set to be 2%, preferably 20% or less. According to such a configuration, by adjusting the dimensional ratio of materials having different elongation amounts, the difference in the longitudinal and lateral elongation amounts can be reduced, so that the printing accuracy can be improved.

In addition, each component illustrated in the above embodiment may be deleted, and the shape, structure, material, and the like of each component may be changed. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment.
By adjusting the dimensional ratio of the materials, the difference in the amount of vertical and horizontal elongation can be reduced, so the printing accuracy can be improved.

DESCRIPTION OF SYMBOLS 10 ... Screen printer, 12 ... Holding member, 13 ... Squeegee, 20, 20A ... Screen mask, 20a ... Front surface, 20b ... Back surface, 21 ... Frame, 22 ... Mesh, 22a ... Warp, 22b ... Weft, 23 ... Mask membrane 23a, 123a ... pattern opening, 23c ... step, 26 ... main mesh, 26a ... warp, 26b ... weft, 26c ... hole, 27 ... support mesh, 27a ... warp, 27b ... weft, 28 ... lighting, Pe ... coating Material, C1... Spacing, R1... Large portion (large diameter portion), R2... Small width portion (small diameter portion).

Claims (5)

A support material having holes through which the coating material can pass;
A mask film provided on the support material, having a step or an inflection in the middle of the film thickness direction and having a pattern opening whose opening width on the printing surface side is narrower than the opening width on the opposite side mask.   2. The pattern opening has an inclination angle of 20 degrees or less between a peripheral wall from the step or the inflection part to the printing surface and a peripheral wall from the step or the inflection part to the opening on the opposite side. The screen mask described.   The screen mask according to claim 1, wherein a difference between the opening width on the printing surface side and the opening width on the opposite side is 40 μm or less.   A mask film formed on a support material having holes that can pass through the coating material is exposed multiple times from one surface side, so that there is a step or inflection in the middle of the film thickness direction. And forming a pattern opening whose opening width on the one surface side is narrower than the opening width on the opposite side.   5. The method of manufacturing a screen mask according to claim 4, wherein the plurality of exposures are maskless exposures.